:root {
    --bg: #ffffff;
    --surface: #ffffff;
    --text: #1f2937;
    --muted: #6b7280;
    --line: #e5e7eb;
    --brand: #111827;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
    background: transparent;
    color: var(--text);
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
}

.app-shell {
    max-width: 1100px;
    margin: 0 auto;
    padding: 16px 14px 84px;
}

.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}
.app-title {
    margin: 0;
    font-size: 22px;
    font-weight: 700;
}
.app-subtitle {
    color: var(--muted);
    font-size: 13px;
}

.card {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 10px;
}

.btn {
    display: inline-block;
    text-decoration: none;
    border: 1px solid #cbd5e1;
    background: #fff;
    color: var(--text);
    padding: 8px 12px;
    border-radius: 8px;
    font-size: 13px;
    cursor: pointer;
}
.btn.primary {
    background: var(--brand);
    border-color: var(--brand);
    color: #fff;
}

.bottom-nav {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.96);
    border-top: 1px solid var(--line);
    -webkit-backdrop-filter: blur(6px);
    backdrop-filter: blur(6px);
}
.bottom-nav-inner {
    max-width: 1100px;
    margin: 0 auto;
    padding: 8px 10px calc(8px + env(safe-area-inset-bottom));
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
}
.nav-item {
    text-decoration: none;
    color: var(--muted);
    text-align: center;
    font-size: 12px;
    padding: 8px 4px;
    border-radius: 8px;
}
.nav-item.active {
    background: #f3f4f6;
    color: var(--brand);
    font-weight: 700;
}

.notice {
    margin: 10px 0;
    padding: 10px 12px;
    border-radius: 8px;
    border: 1px solid #bbf7d0;
    background: #f0fdf4;
    color: #166534;
    font-size: 13px;
}
.error {
    margin: 10px 0;
    padding: 10px 12px;
    border-radius: 8px;
    border: 1px solid #fed7aa;
    background: #fff7ed;
    color: #9a3412;
    font-size: 13px;
}

@media (max-width: 640px) {
    .app-shell { padding: 12px 10px 86px; }
    .app-title { font-size: 20px; }
}